Relatives will be taken by US-chartered planes, or via commercial flights with their fares paid by the Department of Defense, to a number of safe havens in the US.

After 30 days, the evacuees will be told whether they should return to Japan or remain where they are.

In the meantime, a nine-member nuclear hazard team from the US will be sent to Japan, where it will be tasked with evaluating the risks posed by the unfolding reactor crisis.

The US military is shipping extra supplies of potassium iodide to Japan for use by the military, but Lapan described it as a precautionary move.

The Pentagon also announced Thursday it had authorized up to $35 million in humanitarian assistance to Japan. To date 40 tons (36.3 tonnes) of relief has been delivered by the US military, including milk, water, blankets and food.

US President Barack Obama said Thursday he would make a statement on Japan, which is battling multiple disasters after a huge earthquake, later in the day.

British and American search and rescue teams will end their operations in Japan Friday and begin to pull out of the quake-stricken country.

“We are all extremely proud of the work of the UK Fire and Rescue team. Sadly, the chance of them finding further survivors is now extremely low and so their specialist skills are no longer necessary in Japan,” Andrew Mitchell, Britain’s international development secretary said.

“We have therefore agreed with the Japanese authorities that we will withdraw our team.”